Gerotor type pump



April 28,1964 s. JOHNSON 3,130,630

GEROTOR TYPE PUMP Filed May 51, 1962 F l e. z

. INVENTOR. ARTHUR s. JOHNSON ATTQRNEYS United States Patent C) 3,130,680 GEROTOR TYPE PUMP Arthur S. Johnson, Warwick, R.I., assignor to Brown 81 Sharpe Manufacturing Company, a corporation of Rhode Island Filed May 31, 1962, Ser. No. 199,156 1 Claim. (Cl. 103- 118) This invention relates to a Gerotor type pump for pumping fluids.

In prior constructions where there has been a motor having a shaft to drive one pump element with the other element mounted in a housing, it has been usual to provide two different bores in the housing which are eccentric one with reference to the other for the purposes of eccentrically mounting one of the elements. This eccentric boring required at least two different steps together with an accurate setup for each such boring.

One of the objects of this invention is to provide a construction which will eliminate certain steps in the formation of the pump.

Another object of this invention is to provide a pump which which will be of such construction that one bore may be provided instead of the two bores heretofore used.

Another object of the invention is to provide a construction, the design of which is adapted for several sizes of pumps all of which may be produced in a more economical manner.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claim.

In the accompanying drawings:

FIG. 1 is an elevation partly in section showing a motor with the pump housing utilized in this invention;

FIG. 2 is a section on line 2-2 of FIG. 1; and

FIG. 3 is a longitudinal section taken at generally right angles to the section shown in FIG. 1.

In proceeding with this invention, I have provided a boss surrounding the motor drive shaft, which boss has its outer surface cylindrical but located on an axis eccentric to the axis of the shaft, and I have provided a housing for the pump which may fit over this boss snugly having an O-ring seal therewith and which housing has a bore of one uniform cylindrical diameter throughout its length, thus positioning the bore of the housing eccentric to the axis of the shaft. This housing bore will contain one of the elements of the pump while the other element of the pump will be mounted on the axis of the shaft, the pump being of a usual form so far as the two elements are concerned.

With reference to the drawings, designates an electric motor having a drive shaft 11 extending outwardly therefrom. A boss 12 extends from one end of the motor surrounding the shaft 11 and has an inner bore 13 concentric with the shaft. However, the outer surface 14 of the boss is cylindrical but is eccentric to the axis of the shaft 11 as may be seen in FIG. 2.

The pump housing 15 is provided with a single uniform cylindrical bore 16 of a size to fit over the cylindrical outer surface 14 of the boss, and by reason of an elastic O-ring 17 in a recess 18 of the boss, a seal is provided with the boss. This housing is provided with a flange 19 which may be used to hold the housing snugly on the boss and against a shoulder 20 on the boss.

By reason of the eccentricity of the surface. 14 of the boss, the bore 16 of the housing is mounted eccentric to the axis of the shaft 11 which affords an opportunity for the mounting of the element 21 of the pump eccentric to the axis of the shaft 11, while the other or second element of the pump 22 may be mounted on the axis of the shaft 11 and keyed thereto as at 23 so as to rotate with this shaft. These pump elements are of the usual construction in which there is one more pocket 24 in the element 21 than there are prongs 25 in the element 22 so that, as rotation occurs, liquid will be drawn in through the opening 26 in the housing 15 and discharged through opening 27 in the housing when the pump is rotated in one direction. This construction being symmetrical, it is perfectly possible for rotation of the shaft in the other direction to cause the liquid to be drawn through the opening 27 and discharged through the opening 26. A fitted washer 28 forms a barrier between the pumping cavities and the inner bore 13. A seal 29 is provided on the shaft 11 at the location of one of the intermediate diameters 30 of the shaft, but should any of the liquid pass this seal, it will drain through the opening 31. A back drain connection is provided through the opening 32 as shown in FIG. 1 and is piped back to asource of supply. One function of the back drain is to take fluid that may pass externally of washer 28 into bore 13 and return it between shaft 11 and the inner bore of washer 28, then through the extra keyway 34 and finally to opening 32. This avoids pressure build-up against seal 29. A pin 33 in drilled hole in washer 28 and in boss 12 pre- Vents any appreciable relative rotation between these two parts.

By reason of the providing of the cylindrical outer surfaace of the boss 14 eccentric to the axis of the shaft, I am able to utilize a uniform single diameter bore in the housing 15 so that it may contain the pump element 21 locating it eccentric to the axis of the shaft and thus making only one boring operation necessary in the housing for the accomplishment of the location of the pump element eccentrically as above explained and thus eliminating the need for two bores on different axes in the housing as had heretofore been utilized, thus materially reducing the time needed for the boring operations and reducing the cost of manufacture.

I claim:

In a Gerotor type pump,

(a) a motor having a drive shaft extending therefrom,

(b) a boss extending from the motor and surrounding the shaft with its outer surface cylindrical and eccentric to the axis of the shaft,

(0) a pump housing having a single cylindrical bore of a size to fit the outer surface of said boss and extending thereover,

(d) an outer pump element having an outer surface fitting and located in said housing bore,

(e) an inner pump element keyed to the drive shaft cooperating with said outer element,

(3) said pump housing having inlet and outlet openings for receiving and discharging liquid.

References Cited in the file of this patent UNITED STATES PATENTS 1,725,390 Brouse Aug. 20, 1929 2,246,276 Davidson June 17, 1941 2,862,452 Lung Dec. 2, 1958 2,968,251 Eames Jan. 17, 1961 3,013,500 Bollibon Dec. 19, 1961 

